Adjusted Survival Curves Improve Understanding of Multivariable Cox Model Results

Kaplan-Meier survival curves are the most common method for unadjusted group comparison of outcomes in orthopedics research. However, they may be misleading due to an imbalance of confounders between patient groups. The Cox model is frequently used to adjust for confounders, but graphical display of adjusted survival curves is not commonly utilized. We describe the circumstances when adjusted survival curves are useful in orthopedic research, describe and use two different methods to obtain adjusted curves, and illustrate how they can improve understanding of the multivariable Cox model results. We further provide practical strategies for identifying the need for and performing adjusted survival curves.